php magic function concentration camp_PHP tutorial

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php tutorial magic function concentration camp

1. __construct()

Called when instantiating an object,

When __construct and a function with the class name and function name exist at the same time, __construct will be called and the other will not be called.

　2. __destruct()

Called when an object is deleted or the object operation terminates.

3. __call()

The object calls a method,

If the method exists, call it directly;

If it does not exist, the __call function will be called.

4. __get()

When reading the properties of an object,

If the attribute exists, return the attribute value directly;

If it does not exist, the __get function will be called.

5. __set()

When setting the properties of an object,

If the attribute exists, assign the value directly;

If it does not exist, the __set function will be called.

6. __toString()

Called when printing an object. Such as echo $obj; or print $obj;

7. __clone()

Called when cloning an object. For example: $t=new Test();$t1=clone $t;

8. __sleep()

serialize was called before. If the object is relatively large and you want to delete a few things before serializing, you can consider this function.

9. __wakeup()

It is called when unserialize and does some object initialization work.

10. __isset()

Called when checking whether an object's property exists. For example: isset($c->name).

11. __unset()

Called when unsetting a property of an object. For example: unset($c->name).

12. __set_state()

Called when var_export is called. Use the return value of __set_state as the return value of var_export.

13. __autoload()

When instantiating an object, if the corresponding class does not exist, this method is called.

Magic constants

1. __LINE__

Returns the current line number in the file.

　2. __FILE__

Returns the full path and file name of the file. If used in an include file, returns the include file name. As of PHP 4.0.2, __FILE__ always contains an absolute path, while versions before that sometimes contained a relative path.

3. __FUNCTION__

Return function name (newly added in PHP 4.3.0). Since PHP 5 this constant returns the name of the function as it was defined (case sensitive). In PHP 4 this value is always lowercase.

　4. __CLASS__

Returns the name of the class (new in PHP 4.3.0). Since PHP 5 this constant returns the name of the class when it was defined (case sensitive). In PHP 4 this value is always lowercase.

5. __METHOD__

Return the method name of the class (newly added in PHP 5.0.0). Returns the name of the method when it was defined (case-sensitive).